SEASIDE PARK, N.J. (AP) — Continuing hot spots could hamper investigators trying to figure out the cause of a fire that charred four blocks of bars, pizza shops and T-shirt stands — perhaps 50 businesses in all — on a Jersey shore boardwalk that still was trying to recover from Superstorm Sandy.

The initial problem is spots where flames could keep flaring up among the rubble from the blaze that shot fireballs 50 feet into the sky Thursday night before crews got it contained.

In a news briefing Friday, Gov. Chris Christie said it would be “irresponsible for any of us to speculate” what sparked the fire that is believed to have started in or near a frozen custard stand.

He said the firefighters working on spraying down any flare-ups are also doing their best to preserve evidence for the fire investigation team that’s trying to piece together just what happened.

In the meantime, plans to rebuild again already are in the works.

Bob Martucci, the borough administrator in Seaside Park, said it will cost $600,000 to rebuild the borough-owned boardwalk that was burned in his town. That would cover just the stretch of boardwalk itself, not the businesses that were ruined.

Christie said Friday that government grants or loans could be made available to businesses to cover costs that insurance will not cover.

“I will not permit all the work we’ve done over the last 10 months to be diminished or destroyed by what happened last night,” he said Friday as he stood across the street from a still-smoldering pizza shop and a gutted arcade that he used to patronize with his family.

U.S. Rep. Frank Pallone, a Democrat whose district is just a few miles from the boardwalk, said he would ask if federal money sent to towns to rebuild after Sandy could be used to help.

The boardwalk itself, battered by Sandy last October, was rebuilt five months ago. One of the big attractions in the stretch — the Funtown amusement pier — had not reopened after Sandy. It burned in the fire, with its landmark “Funtown Pier” sign collapsing in a cloud of flames and sparks, falling on the gray charred remains of a once colorful attraction.

Among the businesses destroyed were a fudge shop, fry stands and a bar and grill where Nicole “Snooki” Polizzi was punched in the face during filming of the first season of MTV’s “Jersey Shore.”

Paul Schneider, who owns three small boardwalk stands, had to rip out damaged electrical wiring and replace sodden merchandise after Sandy.

“Everything’s gone. I can’t believe this is happening again,” he said.